But getting to the bottom of the fossil collection and documenting it all took researchers about 10 years.
Discovering the Fossils
In 2013, an employee at Dinosaur Park – a small fossil preserve in Laurel, Maryland – first spotted something blue-green buried in the ground. The former riverbed and mining site had a long history of fossil finds, which tended to reveal themselves with such an aquamarine glimmer. Park staff looked over the spot and decided to leave the bone encased in ironstone and use it for educational purposes.
In 2014, a chance encounter between the same stone and “a piece of heavy landscaping machinery,” TheBaltimore Sun writes, exposed more of the fossil. The collision came as a shock, but scientists at the park decided to let nature erode the ironstone further.
The staff later changed their minds and began to excavate the area in 2021 and found many more fossils that dated to about 115 million years ago. The researchers first came across a 4-foot limb bone, which remains unidentified, and slowly uncovered more as they kept digging.
At the small, 3.63-acre site, paleontologist J.P. Hodnett and others uncovered a 3-foot-long shin bone belonging to a large theropod, the same group of dinosaurs as Tyrannosaurus rex. But these bones predate T. rex and likely belonged to an Acrocanthosaurus, the largest theropod in the Early Cretaceous period. That made the bone the largest theropod fossil ever found in eastern North America.
As the team dug, it found more and more bones, something unfitting for the eastern half of the country. Large assemblages or “bone beds” are more common in the western U.S., where paleontologists find more exposed stone.